Fiber optic probes of the kind adapted for immersion in a fluid medium conventionally are formed of a plurality o materials. Such materials have different thermal expansion and contraction characteristics. To compensate for such differences it has been conventional heretofore to utilize deformable, resilient, elastomeric seals and apply static compression forces on the seals of such magnitude as to prevent leakage.
Examples of conventional sealing techniques are disclosed in U.S. Pat. Nos. 4,573,761 and 4,707,134. Although such seals function satisfactorily for somewhat limited periods of time, they are susceptible to deterioration and consequent leakage after a few months, particularly in those instances in which the probes are used in environments where large temperature variations routinely are encountered and where extensive use and consequent movements of the probes results in relieving the static compressive force applied on the seals.
Deterioration of the seals of conventional constructions may be accelerated in those instances where the sealing structure is subjected to torque tending to rotate either the seals themselves or some structural member in engagement with such seals. Such rotation tends to abrade the seals, thereby hastening their failure.
In combatting the adverse effects of unequal thermal contraction and expansion of different materials, it has been the practice heretofore to utilize materials whose thermal expansion and contraction characteristics were sufficiently similar to minimize the inequalities. This practice, however, sometimes has resulted in having to utilize materials having less than optimum corrosion resistance and/or optical properties.
A principal object of the present invention is to provide a sealed probe construction which overcomes the disadvantages referred to above.